Flask



FIG. 1 is a top perspective view of a flask showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a right side elevation view thereof, the left side elevation view being a mere image;

FIG. 5 is a rear elevation view thereof; and,

FIG. 6 is a front elevation view thereof. 

The ornamental design for a flask, as shown and described. 